When the next big earthquake will strike


hat happened
Scientists say it is nearly certain that a massive earthquake will strike California in the next 30 years. A comprehensive geologic survey released Monday said there is a 99 percent chance that the fault-laced state will be hit by a temblor measuring 6.7 on the Richter scale, and there’s a 50 percent chance that a magnitude 7.5 quake will strike. That would be large enough to cause catastrophic damage if it affects a major city, such as San Francisco or Los Angeles (Reuters)

What the commentators said
“Death and taxes are said to be life's only certainties,” said Julie Sevrens Lyons in the San Jose Mercury News (free registration), but it looks like we can add “another calamity to that list: earthquakes.” The big surprise from this report was that these researchers gave Northern and Southern California an equal chance of being rattled by a magnitude 6.7 quake, as the conventional wisdom identified the southern part of the state as the most likely target.

Southern California is more likely to face a truly catastrophic quake, said Hector Becerra in the Los Angeles Times (free registration). The possibility of a magnitude 7.5 quake—which “shakes at 16 times the intensity of a 6.7 quake” such as the 1994 Northridge quake—is 37 percent in Southern California and 15 percent in Northern California. But the report didn’t say what everyone really wants to know—exactly “where the expected 6.7 quake will hit—or when.”

Let this report serve as a reminder, said David Perlman in the San Francisco Chronicle. “California, riven by thousands of faults that extend many miles deep into the Earth's crust, is one of the world's most seismically active regions.” Two giant tectonic segments of the Earth's crust—the Pacific Plate and the North American Plate—move constantly past each other at about an inch and a half a year, “forming a great clashing boundary where stresses build up” and, inevitably, rupture to “release an earthquake’s power.”


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